Method and apparatus for joule carbonization or graphitization of fibers made from intrinsically electrically-conductive polymers

ABSTRACT

A method for joule carbonization of fibers includes subjecting the fibers, made from an intrinsically electrically-conductive material, to a current density sufficient to heat the fibers to a carbonization temperature of between 900-2000° C. whereby the fibers are carbonized into carbon fibers. A method for joule graphitization of fibers includes subjecting the fibers, made from an intrinsically electrically-conductive material, to a current density sufficient to heat the fibers to a graphitization temperature of between 2400-3000° C. whereby the fibers are graphitized into graphitic carbon fiber.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application Ser. No. 63/337,811, filed on May 3, 2022, which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

This document relates generally to the carbonized fiber field and, more particularly, to a new and improved method and apparatus for the joule carbonization or graphitization of fibers made from intrinsically electrically-conductive polymers.

BACKGROUND

Carbonized fibers or carbon fibers have a number of unique physical characteristics that make them particularly suited for a wide range of engineering applications. These characteristics include, but are not necessarily limited to, a high strength-to-weight ratio, high tensile strength, high stiffness, high chemical resistance, low thermal expansion and high-temperature tolerance. This has led to wide application and use of these fibers in the automobile, aircraft, aerospace and wind energy industries.

More specifically, the carbon fibers are typically combined with other materials to form composites such as carbon fiber reinforced polymers, having high strength-to-weight ratios. When carbon fibers are combined with graphite, reinforced carbon-carbon composites, with very high heat tolerance, result.

Unfortunately, as a result of state of the art processing, carbon fibers are more expensive to produce than similar fibers made from glass, basalt or plastic. This has been a limiting factor in their adoption and use for more wide ranging applications. This document relates to a new and improved method and apparatus for the joule carbonization/graphitization of fibers made from intrinsically electrically-conductive polymers. Advantageously, the precursor intrinsically electrically-conductive polymer fibers can be carbonized/graphitized without any oxidation or stabilization processing prior to passing a current through the fibers to complete the carbonization/graphitization. Thus, the production of carbon fibers becomes a simple two step process of spinning the intrinsically conductive polymer precursor fibers to desired specifications and then subjecting the spun fibers to joule heating resulting in the carbonization/graphitization of the fibers. This is a quick and efficient method for producing carbon/graphitic fibers that should lower (a) greenhouse gas emissions, (b) embodied energy in the fibers and (c) manufacturing costs.

SUMMARY

In accordance with the purposes and benefits set forth herein, a method is provided for the joule carbonization of fibers that method comprises, consists of or consists essentially of the step of subjecting the fibers, made from an intrinsically electrically-conductive material, to a current density sufficient to heat the fibers to a carbonization temperature of between about 900° C. to about 2000° C. whereby the fibers are carbonized into carbon fibers.

Toward this end, in one or more of the many possible embodiments of the method, the method includes the step of feeding the fibers across a first electrically conductive roller and a second electrically conductive roller. Still further, the method includes applying a current across the first electrically conductive roller and the second electrically conductive roller. In addition, the method may include balancing, by a controller, (a) rotation speeds of the first electrically conductive roller and the second electrically conductive roller and (b) the current density of the applied current to allow continuous processing of the fiber. This may include the applying of the current to the fiber without any previous oxidation or stabilization processing of the fiber.

In at least one embodiment, the method includes selecting the fibers from a group of fibers made from intrinsically electrically conductive materials consisting of a polyacetylene, a polythiophene, a polypyrrole, a polyaniline, a polyphenylene, a derivative thereof and polymer blends thereof.

In accordance with an additional aspect, a method is provided for the joule graphitization of fibers. This method comprises, consists of or consists essentially of subjecting the fibers, made from an intrinsically electrically-conductive material, to a current density sufficient to heat the fibers to a graphitization temperature of between about 2400° C. to about 3000° C. whereby the fibers are graphitized into graphitic carbon fibers.

Toward this end, the method may include one or more of the following additional steps:

-   -   (a) feeding the fibers across a first electrically conductive         roller and a second electrically conductive roller;     -   (b) applying a current across the first electrically conductive         roller and the second electrically conductive roller;     -   (c) balancing, by a controller, (a) rotation speeds of the first         electrically conductive roller and the second electrically         conductive roller and (b) the current density the applied         current to allow continuous processing of the fiber;     -   (d) applying of the current to the fiber without any previous         oxidation or stabilization processing of the fiber; and     -   (e) selecting the fibers from a group of fibers made from         intrinsically electrically conductive materials consisting of a         polyacetylene, a polythiophene, a polypyrrole, a polyaniline, a         polyphenylene, a derivative thereof and polymer blends thereof.

In accordance with yet another aspect, an apparatus for the joule carbonization or graphitization of fibers made from intrinsically electrically-conductive polymers, comprises, consists of or consists essentially of:

-   -   a first electrically conductive roller;     -   a second electrically conductive roller;     -   a current source having a positive terminal connected to one of         the first electrically conductive roller and the second         electrically conductive roller and a negative terminal connected         to another of the first electrically conductive roller and the         second electrically conductive roller; and     -   a drive motor system adapted for driving the first electrically         conductive roller and the second electrically conductive roller.

In one or more of the many possible embodiments of the apparatus, the apparatus further includes a source of intrinsically electrically-conductive fiber adapted for feeding the fiber that is serially looped around the first electrically conductive roller and the second electrically conductive roller.

In at least some embodiments, the apparatus includes a support, wherein the first electrically conductive roller and the second electrically conductive roller are carried on the support and freely rotate with respect to the support.

In at least some embodiments, the apparatus includes a controller operatively connected to the current source, the first drive motor and the second drive motor. The controller is adapted to balance (a) rotation speeds of the first electrically conductive roller and the second electrically conductive roller and (b) a current density of a current applied across the first electrically conductive roller and the second electrically conductive roller, to allow continuous processing of the fiber. For any embodiment of the apparatus, the fibers may be made from an intrinsically electrically conductive material consisting of a polyacetylene, a polythiophene, a polypyrrole, a polyaniline, a polyphenylene, a derivative thereof and polymer blends thereof.

In the following description, there are shown and described several different embodiments of the new and improved method and apparatus for processing fibers made from intrinsically electrically-conducting material. As it should be realized, that method and apparatus are capable of other, different embodiments and their several details are capable of modification in various, obvious aspects all without departing from the method as set forth and described in the following claims. Accordingly, the drawings and descriptions should be regarded as illustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The accompanying drawing figures incorporated herein and forming a part of the specification, illustrate certain aspects of the apparatus and method and together with the description serve to explain certain principles thereof. A person of ordinary skill in the art will readily recognize from the following discussion that alternative embodiments of the illustrated structures and methods may be employed without departing from the principles described below.

FIG. 1 is a schematic diagram of the apparatus used for the joule carbonization or graphitization of fibers made from intrinsically electrically-conductive polymers.

FIG. 2 is a schematic block diagram illustrating the controller of the apparatus connected to the first and second drive motors and the current source.

Reference will now be made in detail to the present preferred embodiments of the apparatus and method.

DETAILED DESCRIPTION

As noted above, the method and apparatus 10 allow for joule heating and the carbonization or graphitization of intrinsically, electrically-conductive polymer fibers F. Such fibers may be made, for example, from:

-   -   One or more polyacetylenes     -   One or more polythiophenes such as poly (3-alkylthiophene)         (P3HT) and poly (3,4-ethylenedioxythiophene (PEDOT).     -   One or more polypyrroles     -   One or more polyanilines     -   One or more polyphenylenes such as poly(phenylene vinylene) and         poly(2,5-dialkoxy-p-phenylene vinylene)     -   Also including their complexed derivatives and blends such as         poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)         (PEDOT:PSS).

Fiber diameters are typically in the range of between about 5 and about 15 microns. Fiber shapes are typically round in cross section but could also be bean shaped or any other shape. Any number of fibers may be processed at any one time from a single fiber to large tows of fibers.

As shown in the drawing FIGS. 1 and 2 , the apparatus 10 for the joule heating and carbonization or graphitization of the intrinsically conductive polymer fibers F includes a support 12, including a base 14 and an upright housing 16. In the illustrated embodiment, the apparatus 10 also includes a current source 18 having a positive terminal 20 connected to a first electrically conductive roller 22 and a negative terminal 24 connected to a second electrically conductive roller 26. In an alternative embodiment (not shown), the positive terminal 20 is connected to the second electrically conductive roller 26 and the negative terminal 24 is connected to the first electrically conductive roller 22.

The first and second conductive rollers 22, 26 may be driven for rotation by a drive motor system 28, 30. In the illustrated embodiment, the drive motor system 28, 30 includes a first drive motor 28 that drives the first conductive roller 22 and a second drive motor 30 that drives the second conductive roller 26. The rollers 22, 26 may be driven at the same or different speeds. In an alternative embodiment (not shown), the drive motor system 28, 30 comprises a single drive motor that drives both of the conductive rollers 22, 26 at the same or different speeds through appropriate gearing. In any of the embodiments, the first and second electrically conductive rollers 22, 26 may be carried for rotation on the upright housing 16 as shown.

The intrinsically electrically-conductive polymer fibers F are fed from a source of fiber supply (see, for example, reel 32) and serially looped around the first conductive roller 22 and the second conductive roller 26 under an inert atmosphere of, for example, nitrogen gas. As the fibers F pass between the rollers 22, 26, current is applied across the first and second conductive rollers causing the fibers to be subjected to a current density sufficient to heat the fibers to a carbonization temperature of between about 900° C. and about 2000° C. whereby the intrinsically conductive polymer fibers are carbonized into carbon fiber. In some embodiments, the carbonization temperature is between about 1,000° C. and about 1500° C. and in some embodiments, the carbonization temperature is about 1,300° C.

As best shown in FIG. 2 , the apparatus 10 may also include a controller 34, in the form of a computing device such as a dedicated microprocessor or software controlled electronic controller. That controller 34 is operatively connected to and controls the operation of the first and second drive motors 28, 30 and the current source 18. Further, the controller 34 is adapted for carefully balancing the rotation speeds of the first and second rollers 22, 26 and the current density of the applied current to allow continuous processing of the fibers F into carbon fibers which may then be cooled and taken up on a processed carbon fiber reel (not shown).

In still other possible embodiments, the fibers F being fed between the rollers 22, 26 are subjected to a current density sufficient to heat the fibers F to a graphitization temperature of between about 2,400° C. and about 3,000° C. whereby the intrinsically electrically-conductive polymer fibers are graphitized into graphitic carbon fibers.

Advantageously, the precursor intrinsically electrically-conductive polymer fibers F can be carbonized/graphitized without any oxidation or stabilization processing prior to passing a current through the fibers to complete the carbonization/graphitization. Thus, the production of carbon/graphitic carbon fibers becomes a simple two step process of spinning the intrinsically electrically-conductive polymer precursor fibers to desired specifications and then subjecting the spun fibers to joule heating resulting in the carbonization or graphitization of the fibers. This is a quick and efficient method for producing carbon or graphitic carbon fibers that should lower (a) greenhouse gas emissions, (b) embodied energy in the fibers and (c) manufacturing costs.

This disclosure may be said to relate to the following items.

-   -   1. A method for joule carbonization of fibers, comprising:         -   subjecting the fibers, made from an intrinsically             electrically-conductive material, to a current density             sufficient to heat the fibers to a carbonization temperature             of between 900-2000° C. whereby the fibers are carbonized             into carbon fibers.     -   2. The method of item 1, further including feeding the fibers         across a first electrically conductive roller and a second         electrically conductive roller.     -   3. The method of item 2, further including applying a current         across the first electrically conductive roller and the second         electrically conductive roller.     -   4. The method of item 3, further including balancing, by a         controller, (a) rotation speeds of the first electrically         conductive roller and the second electrically conductive roller         and (b) the current density of the applied current to allow         continuous processing of the fiber     -   5. The method of item 4, further including the applying of the         current to the fiber without any previous oxidation or         stabilization processing of the fiber.     -   6. The method of item 1, including selecting the fibers from a         group of fibers made from intrinsically electrically conductive         materials consisting of a polyacetylene, a polythiophene, a         polypyrrole, a polyaniline, a polyphenylene, a derivative         thereof and polymer blends thereof.     -   7. A method for joule graphitization of fibers, comprising:         -   subjecting the fibers, made from an intrinsically             electrically-conductive material, to a current density             sufficient to heat the fibers to a graphitization             temperature of between 2400-3000° C. whereby the fibers are             graphitized into graphitic carbon fibers.     -   8. The method of item 7, further including feeding the fibers         across a first electrically conductive roller and a second         electrically conductive roller.     -   9. The method of item 8, further including applying a current         across the first electrically conductive roller and the second         electrically conductive roller.     -   10. The method of item 9, further including balancing, by a         controller, (a) rotation speeds of the first electrically         conductive roller and the second electrically conductive roller         and (b) the current density of the applied current to allow         continuous processing of the fiber.     -   11. The method of item 10, further including the applying of the         current to the fiber without any previous oxidation or         stabilization processing of the fiber.     -   12. The method of item 7, including selecting the fibers from a         group of fibers made from intrinsically electrically conductive         materials consisting of a polyacetylene, a polythiophene, a         polypyrrole, a polyaniline, a polyphenylene, a derivative         thereof and polymer blends thereof.     -   13. An apparatus for joule carbonization or graphitization of         fibers made from intrinsically conductive polymers, comprising:         -   a first electrically conductive roller;         -   a second electrically conductive roller;         -   a current source having a positive terminal connected to one             of the first electrically conductive roller and the second             electrically conductive roller and a negative terminal             connected to another of the first electrically conductive             roller and the second electrically conductive roller; and         -   a drive motor system adapted for driving the first             electrically conductive roller and the second electrically             conductive roller.     -   14. The apparatus of item 13, further including a source of         intrinsically electrically-conductive fiber adapted for feeding         the intrinsically conductive fiber that is serially looped         around the first electrically conductive roller and the second         electrically conductive roller.     -   15. The apparatus of item 14, further including a support,         wherein the first electrically conductive roller and the second         electrically conductive roller are carried on the support and         freely rotate with respect to the support.     -   16. The apparatus of item 15, wherein the fibers are made from         an intrinsically electrically conductive material consisting of         a polyacetylene, a polythiophene, a polypyrrole, a polyaniline,         a polyphenylene, a derivative thereof and polymer blends         thereof.     -   17. The apparatus of item 16, further including a controller         operatively connected to the current source and the drive motor         system, the controller being adapted to balance (a) rotation         speeds of the first electrically conductive roller and the         second electrically conductive roller and (b) a current density         of a current applied across the first electrically conductive         roller and the second electrically conductive roller, to allow         continuous processing of the fiber.     -   18. The apparatus of item 13, further including a controller         operatively connected to the current source and the drive motor         system, the controller being adapted to balance (a) rotation         speeds of the first electrically conductive roller and the         second electrically conductive roller and (b) a current density         of a current applied across the first electrically conductive         roller and the second electrically conductive roller, to allow         continuous processing of the fiber.

Each of the following terms written in singular grammatical form: “a”, “an”, and “the”, as used herein, means “at least one”, or “one or more”. Use of the phrase “One or more” herein does not alter this intended meaning of “a”, “an”, or “the”. Accordingly, the terms “a”, “an”, and “the”, as used herein, may also refer to, and encompass, a plurality of the stated entity or object, unless otherwise specifically defined or stated herein, or, unless the context clearly dictates otherwise. For example, the phrase: “a polyacetylene”, as used herein, may also refer to, and encompass, a plurality of polyacetylenes.

Each of the following terms: “includes”, “including”, “has”, “having”, “comprises”, and “comprising”, and, their linguistic/grammatical variants, derivatives, or/and conjugates, as used herein, means “including, but not limited to”, and is to be taken as specifying the stated component(s), feature(s), characteristic(s), parameter(s), integer(s), or step(s), and does not preclude addition of one or more additional component(s), feature(s), characteristic(s), parameter(s), integer(s), step(s), or groups thereof.

The phrase “consisting of”, as used herein, is closed-ended and excludes any element, step, or ingredient not specifically mentioned. The phrase “consisting essentially of”, as used herein, is a semi-closed term indicating that an item is limited to the components specified and those that do not materially affect the basic and novel characteristic(s) of what is specified.

Terms of approximation, such as the terms about, substantially, approximately, etc., as used herein, refers to ±10% of the stated numerical value.

Although the method and apparatus of this disclosure have been illustratively described and presented by way of specific exemplary embodiments, and examples thereof, it is evident that many alternatives, modifications, or/and variations, thereof, will be apparent to those skilled in the art. Accordingly, it is intended that all such alternatives, modifications, or/and variations, fall within the spirit of, and are encompassed by, the broad scope of the appended claims. 

What is claimed:
 1. A method for joule carbonization of fibers, comprising: subjecting the fibers, made from an intrinsically electrically-conductive material, to a current density sufficient to heat the fibers to a carbonization temperature of between 900-2000° C. whereby the fibers are carbonized into carbon fibers.
 2. The method of claim 1, further including feeding the fibers across a first electrically conductive roller and a second electrically conductive roller.
 3. The method of claim 2, further including applying a current across the first electrically conductive roller and the second electrically conductive roller.
 4. The method of claim 3, further including balancing, by a controller, (a) rotation speeds of the first electrically conductive roller and the second electrically conductive roller and (b) the current density of the applied current to allow continuous processing of the fiber.
 5. The method of claim 4, further including the applying of the current to the fiber without any previous oxidation or stabilization processing of the fiber.
 6. The method of claim 1, including selecting the fibers from a group of fibers made from intrinsically electrically conductive materials consisting of a polyacetylene, a polythiophene, a polypyrrole, a polyaniline, polyphenylene, a derivative thereof and polymer blends thereof.
 7. A method for joule graphitization of fibers, comprising: subjecting the fibers, made from an intrinsically electrically-conductive material, to a current density sufficient to heat the fibers to a graphitization temperature of between 2400-3000° C. whereby the fibers are graphitized into graphitic carbon fibers.
 8. The method of claim 7, further including feeding the fibers across a first electrically conductive roller and a second electrically conductive roller.
 9. The method of claim 8, further including applying a current across the first electrically conductive roller and the second electrically conductive roller.
 10. The method of claim 9, further including balancing, by a controller, (a) rotation speeds of the first electrically conductive roller and the second electrically conductive roller and (b) the current density of the applied current to allow continuous processing of the fiber.
 11. The method of claim 10, further including the applying of the current to the fiber without any previous oxidation or stabilization processing of the fiber.
 12. The method of claim 7, including selecting the fibers from a group of fibers made from intrinsically electrically conductive materials consisting of a polyacetylene, a polythiophene, a polypyrrole, a polyaniline, a polyphenylene, a derivative thereof and polymer blends thereof.
 13. An apparatus for joule carbonization or graphitization of fibers made from intrinsically conductive polymers, comprising: a first electrically conductive roller; a second electrically conductive roller; a current source having a positive terminal connected to one of the first electrically conductive roller and the second electrically conductive roller and a negative terminal connected to another of the first electrically conductive roller and the second electrically conductive roller; and a drive motor system adapted for driving the first electrically conductive roller and the second electrically conductive roller.
 14. The apparatus of claim 13, further including a source of intrinsically electrically-conductive fiber adapted for feeding the intrinsically conductive fiber that is serially looped around the first electrically conductive roller and the second electrically conductive roller.
 15. The apparatus of claim 14, further including a support, wherein the first electrically conductive roller and the second electrically conductive roller are carried on the support and freely rotate with respect to the support.
 16. The apparatus of claim 15, wherein the fibers are made from an intrinsically electrically conductive material consisting of a polyacetylene, a polythiophene, a polypyrrole, a polyaniline, a polyphenylens, a derivative thereof and polymer blends thereof.
 17. The apparatus of claim 16, further including a controller operatively connected to the current source and the drive motor system, the controller being adapted to balance (a) rotation speeds of the first electrically conductive roller and the second electrically conductive roller and (b) a current density of a current applied across the first electrically conductive roller and the second electrically conductive roller, to allow continuous processing of the fiber.
 18. The apparatus of claim 13, further including a controller operatively connected to the current source and the drive motor system, the controller being adapted to balance (a) rotation speeds of the first electrically conductive roller and the second electrically conductive roller and (b) a current density of a current applied across the first electrically conductive roller and the second electrically conductive roller, to allow continuous processing of the fiber. 